The present invention relates to a machine and a process for peeling agricultural products. More specifically, it relates to the removal of hulls from nuts, such as pistachios.
As used herein, a peeler is a machine for removing the outer layer from agricultural products, whether or not the product has a distinct outer layer. Those products with a distinct outer layer, such as nuts, have the distinct outer layer removed to leave only the edible or more desirable portion. Those agricultural products without a distinct outer layer may still have their outer portion removed by a peeler in order to remove any portions of the product which may have dirt or other impurities.
Peelers consisting of a rotary disk with an abradant surface turning in a fixed circular motion within a cylinder are common in the food industry and are offered in a variety of configurations. Those skilled in the art of removing the skin or husk from nuts as pistachios currently prefer a peeler using a rotary disk having humps or rises to agitate the product. The disk, which is coated with an abradant such as Carborundum, is mounted in a vertical position and rotates about a fixed location within a cylinder or circular processing chamber at a speed suited for the particular product. A circular processing chamber or cylinder has the disk therein and is equipped with a door for providing an opening in the side for product removal. Vertical non-abrasive ribs (usually in the form of a replaceable liner) are placed about the interior circumference to retard the circular movement of the product while allowing vertical movement. As the abrasive disk under the agricultural product rotates faster than the product, the product is abraded, thus removing its outer layer. Process fluids (such as water) are sprayed into the circular processing chamber onto the product to both soften the skin and wash the peeling or other refuse from the product by a flushing action by a fixed clearance between the spinning rotary disk and processing chamber. A lid is placed on top of the chamber to prevent accidental injury to persons. The lid usually has a door or other means of supplying gravity-fed new product to the processing chamber. Optionally, the means of routing or supporting the necessary plumbing to provide the above-mentioned water is often incorporated with the lid design. A motor is used for turning the rotating disk at a preferred speed. Hydraulic, pneumatic or electric motors are coupled directly or through a drive system to a drive shaft that mounts vertically to a support or frame with an antifriction means such as ball or sleeve bearings that allow circular rotation of the shaft. The rotating disk is fixed at the upper end of the drive shaft, and supported by the drive shaft.
In operation, the processing chamber is filled with a plurality of the product, such as pistachios. An adequate supply of water is then continuously sprayed as the rotary disk spins at a speed that may or may not vary in revolutions per minute. The abrasive action of the rotary disk surface abrades or scraps the skins or husks from the product while the rises or humps located on the rotary disk continually agitates the product in conjunction with the vertical ribs located about the inner periphery of the processing chamber, providing a means of cycling the product in relationship to the abradant action of the rotation disk. As the skin or husk is removed, the water flushes the waste from the system between the rotating disk and the sides of the processing chamber. After the skins or husks have been removed and the rotating disk continues to rotate while the opening in the side is provided, usually by an exit door allowing the centrifugal force to expel the now peeled product from the processing chamber, completing the operation.
The process is usually a continuous batch process where the peeler is maintained in rotation and, following discharge of the peeled product, the exit door is closed and the supply door is opened such that a new batch of product to be processed is supplied into the peeler. Thus, the process includes a cycle of opening a supply door to load the product, closing the supply door, peeling the product through rotation of the peeler, opening an exit door to allow exiting of the processed product, closing the exit door, and repeating the cycle with the peeler maintained in rotation continuous throughout the cycles.
Among prior patents showing various machines for processing agricultural products are the following:
______________________________________ U.S. Pat. No. Inventor ______________________________________ 877,550 C. H. Clark 954,047 R. Powell 1,701,435 G. P. Anstiss 1,902,506 H. L. Johnston et al 1,923,806 G. P. Anstiss 1,945,978 F. J. Palombo et al 2,514,493 H. R. Hetherington 2,769,473 W. R. Comber 2,795,253 R. A. Coleman et al 2,838,083 G. B. Fox et al 3,266,540 C. Bradham 3,762,308 Greene et al 4,442,764 Bos et al 4,768,429 Federighi 5,065,672 Federighi, Sr. ______________________________________
This process to date can only be deemed only partly successful because the random nature of removing the product skins or husks from the processing chamber, the result being the product remains in the peeling device for a process period that extends beyond what is reasonable.
Many prior designs pose a dilemma in choosing their time of use. If the nuts or other agricultural products are removed from the machine too soon, the amounts and likelihood of incompletely processed product (i.e., product having significant portions of peel or hull remaining in place) will be unacceptably high. However, if the nuts or other agricultural products are processed in the peeler machine too long, the amounts and likelihood of damaged product is increased. That is, processing for a long time may not only remove the peels of the products, but may also abrade away non-peel portions of the product, thereby increasing the waste by damaging or reducing the size of individual pieces of the usable output of the process. Depending on the characteristics of the agricultural product being peeled and the peeler, it may be impossible to select a dwell time (time in which abrasive peeling is performed) which avoids both problems. Thus, if one wants to completely peel all of the product, this may necessarily require one to put up with a higher amount of waste than is preferable.
Another disadvantage of many prior peelers is a tendency to wear out some parts faster than is desirable. Often a part called a wear rim wears out faster than is desirable. Upon it wearing out, the wear rim must be replaced right away or the performance of the peeler will be significantly degraded with associated increased product loss.
Another disadvantage of many prior peelers is that the speed used for the peeling results in product damage from excessive battering of the product as it exits the peeler. Also, the speed causes sporadic and uneven flow as the door or doors of the peeler open. However, lowering the speed of rotation used for the peeling lowers the throughput of the peeler (amount of product which can be processed in a given amount of time) and, if lowered sufficiently, may even prevent the peeling from being sufficiently complete.